Effect of spin contamination on the prediction of barrier heights by coupled-cluster theory: F+H2?HF+H reaction
Bibliographic record
Abstract
The role of spin contamination and quasidegeneracy in the energetics of a simple hydrogen abstraction reaction is studied by applying recently developed coupled-cluster (CC) methods to an exactly solvable model for the F+H2→HF+H reaction [C. W. Bauschlicher and P. R. Taylor, J. Chem. Phys. 86, 858 (1987)]. To assess the role of spin contamination, the (spin)-unrestricted Hartree–Fock (UHF) CC with singles and doubles (CCSD) barrier height is compared with that obtained with a fully spin-adapted unitary group approach (UGA) based CCSD, while the quasidegeneracy effects are examined using the so-called reduced multireference (RMR) CCSD method. It is shown that the effect of spin contamination on the barrier height is more significant (0.7 kcal/mol) than that of the quasidegeneracy (0.2 kcal/mol), although the latter plays a more significant role for exothermicity. © 2000 John Wiley & Sons, Inc. Int J Quant Chem 77: 281–290, 2000
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.005 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".